Dispenser



United States Patent f 3,237,571 DISPENSER Douglas F. Corsette, Los Angeles, Calif assignor to Calmar, Inc., City of Industry, Caliii, a corporation of California Filed Dec. 16, 1963, Ser. No. 336,092 13 Claims. (Cl. 103-188) This invention relates to improvements in reciprocating pumps generally and more particularly to improvements in such pumps of the type which are adapted for use as fluid dispensers on portable containers.

In prior known pumps of this type it has been customary to form the parts of the pump insofar as possible of plastic material and to arrange and relate the parts in a manner to facilitate their assembly. Nevertheless due to the lack of an acceptable plastic substitute, it has still been customary in such pumps to employ generally conventional gravity actuated metal ball valves, despite the obvious disadvantages thereof, including relative expense and ditficulty of assembly as well as the need for such valves to conform to quite close tolerances in order to avoid adversely effecting the pump operation.

Also it has been known in such prior pumps to ship the pump with one of the valves maintained in seated position in order to prevent loss or spillage of the container contents in the event of rough handling or inversion during shipment. However prior arrangements for achieving this have all provided for such seating of the valve in a manner which requires that the plunger be maintained fully depressed and which in turn requires the provision of special means for locking or maintain the valve in its depressed condition.

The present invention has been conceived with these factors in mind and accordingly includes among its primary objects to provide an improved pump structure in which all portions thereof except for the plunger re- I turn spring are adapted for formation of usual flexible resilient plastic materials, and to provide such an improved pump structure in which one of the valves is maintained in a fully seated position at either extremity of the plunger or piston stroke. Thus the containers to which the pumps are applied may be safely shipped with the plungers either in their fully depressed conditions, as heretofore been customary, or in their fully projected positions. In the latter case, the means for holding the plunger depressed may be omitted from the pump structure and if desired the projected external portion of the plunger may be covered by a usual protective cap affixed to the container.

It is a further important object of the invention to provide suitable driving connections between the inlet and outlet valves and pump plunger rod in a manner to operate the valves independently of gravity so that the pump may function in any position.

In my copending application Serial No. 318,683, filed October 24, 1963, there are disclose-d pump structures capable of accomplishing the foregoing objects. However, the present invention achieves such objects through a new and different structure including a specifically new construction and manner of operation of the pump outlet valve means.

In accordance with the present invention the reciprocation is imparted to the pump piston through a hollow or tubular piston rod which is slidably disposed through the piston for a limited degree of relative axial movement between predetermined limits, such lost motion at each end of the plunger stroke being utilized to actuate and control the outlet valve means which are provided by cooperating portions of the piston and the hollow plunger, whereby to control the escape of fluid from the 3,237,571 Patented Mar. 1, 1966 pump chamber by way of an outlet passage defined by the hollow plunger rod.

Also in accordance with the invention the inlet valve is frictionally or yieldably coupled to the plunger rod to be seated or unseated at each reversal of the plunger stroke, so that the actions of both valves are properly timed and coordinated with the plunger stroke and with each other and such actuation of the valves in thereby rendered independent of the action of gravity.

In accordance with a still further feature of the invention the stem of the inlet valve, which is frictionally slidably received within the outlet passage of the plunger rod, is partially withdrawn from said passage as an incident to each return or suction stroke of the plunger assembly whereby to provide a suck-back action to prevent drippage of fluid from the pump discharge head or nozzle between compression strokes.

Still further features and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings of a preferred embodiment of the invention in which:

FIGURE 1 is an enlarged longitudinal sectional view of a dispenser of the type described illustrating the application of the invention thereto, the pump plunger or plunger assembly in this view being shown at the end of its suction stroke.

FIGURE 2 is a view similar to FIGURE 1 but with the plunger locked in its fully depressed condition in which it is moved somewhat beyond its usual compression stroke.

FIGURES 3 and 4 respectively are magnified fragmentary sectional views through the pump barrel and plunger assembly showing the parts in the positions which they occupy in FIGURES 1 and 2 respectively.

FIGURE 5 is a cross section on the line 55 of FIGURE 4, and

FIGURE 6 is a cross section on the line 6-6 of FIGURE 4.

Referring now in detail to the accompanying drawings, the dispensing device therein illustrated includes a generally cylindrical pump barrel 10 which, in the present instance, extends through and is supported by a radially enlarged and internally threaded collar portion 11 within the central opening of a container closure 12 (FIGURES 1 and 2) which is adapted by internal threading 14 or otherwise for application to a container such as a bottle or can for the fluid materials to be dispensed. The specific form and construction of the closure 12 and collar 11 and the manner in which they are interconnected are fully disclosed in the copending prior application of the present inventor and Rex C. Cooprider, Serial No. 122,585 filed July 7, 1961, now Patent No. 3,128,018.

Cylinder It) is normally open at its upper end and is formed with an inlet port or passage 16 through its otherwise closed inlet end. This port is defined by an upward extension of the suction tube 18 which depends from the cylinder 10 so that its lower end will normally be disposed closely adjacent the bottom of the container in which the pump is employed, all as is well-known.

The upper end of the pump cylinder 10 opens through the radially enlarged collar 11 for reception of various elements of the pump plunger and valve assemblies. The plunger assembly 20 includes the hollow tubular plunger rod 22 which is adapted to be pressed axially into the cylinder on the pump compression stroke, against the resilient return action of the spring 23 compressed within the pump cylinder between the closed end thereof and the radial enlargement or stop shoulder 42 on the plunger rod. The plunger or plunger assembly also includes the annular or centrally apertured piston 24 which is of the inverted cup-like configuration having a depending skirt 25. This piston is formed separately from the plunger rod 22, the reciprocating motion of which drives the piston, and is disposed for limited axial sliding movement on the plunger rod. The medial portion of the piston immediately surrounding and engaging the plunger rod 22 comprises a sleeve type outlet valve 40 which is formed as an integral part of the piston 24. This outlet valve sleeve 40 is preferably formed of elastically extensible or stretchable material for the reasons more fully set forth later and is slidably disposed on a cooperating reduced diameter external portion 46 of the plunger rod 22 and the relative sliding movement between the piston and plunger rod is limited by engagement of the radially inwardly projecting annular rib 45 of the sleeve valve with the annular stop shoulders-41 and 42 respectively of the plunger rod. This annular rib or collar 45 is preferably an integral portion of the valve sleeve 44) and thus formed of the same elastically extensible material as the remainder thereof. As is shown in FIGURES 2 and 4, the stop shoulders 41 arrest the relative movement between the plunger rod and piston in a position in which the radially opening valve outlet port 44 in the wall of the plunger rod is uncovered by the sleeve valve 40 to place.

the pump chamber 26 in communication through said port with the outlet passage 31 through the plunger rod.

The annular enlargement or stop shoulder 42 is positioned to arrest the relative movement between the plunger rod 22 and piston after the plunger rod has been withdrawn into the sleeve valve 40 sufficiently that the latter covers and closes the port 44.

It will thus be apparent that the piston 24 and the hollow piston rod 22 have a lost motion connection together with cooperating valve means, as above described, which are actuated by such lost motion on each reversal of the plunger stroke and independently of gravity.

In the closed position of the outlet valve, as in FIG- URES 1 and 3, the internal annular rib 45 thereof preferably abuts in sealing relation against the opposing annular face-47 (FIGURE 3) of the coacting stop 42. Thus the stop 42 also acts as a valve means in cooperation with the sleeve valve 49. Preferably the upper or outer end edge of the valve 40 also abuts against a further stop shoulder 48 around the plunger rod 22 for the purpose of supplementing the limiting action of stop shoulder 41.

Moreover the annular rib 45 and the enlargement 42 play an important part in facilitating and maintaining the assembly of their associated parts. To this end the internal diameter of the annular rib 45 is such as to make a freely sliding wiping fit on the reduced external diameter portion 46 of the plunger rod 22, while the outer periphery of the enlargement 42 is of substantially greater diameter so that the rib 45 must be stretched appreciably to permit the enlargement to pass downwardly through it during assembly of the parts. The parts are of course formed of a suitable resiliently flexible and stretchable material such as polypropylene or polyethylene which will permit this action. Moreover to facilitate such action, the annular rib 45 is of downwardly and inwardly converging conical configuration so that its inner periphery may simultaneously flex and stretch downwardly and outwardly into the comparatively larger diameter interior of the immediately adjoining skirt portion 25 of the piston 24 as piston rod 22 is pressed downwardly through the annular rib 45. This same configuration of the rib on the other hand permits the inner edge of the rib to exert a positive axial thrust against the sealing face 47 of the enlargement to improve the efficiency of its sealingaction during the retraction or suction stroke of the plunger assembly.

To facilitate the flow of liquid upwardly between the piston skirt 25 and the outer periphery of enlargement 42, the latter is formed as shown in FIGURE 6 with a plurality of relativelyspaced radial projections 48 which contribute to the efiective external diameter of the enlargement while defining between them a series of fluid flow passages.

The inlet valve 28 is disposed for limited axial movement in the cylinder 10 between seated and unseated positions with respect to the inlet port 16, and is yieldably frictionally connected to the plunger rod 22 for actuation by the plunger rod. Thus the valve 28 is provided with an axially extending cylindrical valve stem 29 proportioned for and snugly frictionally received for sliding movement in a reduced diameter lower end portion 22' of the plunger rod. As will be seen best in FIGURE 3, the outlet port 44 is defined by a slot or notch which opens upwardly through the upper end of this reduced diameter portion or section 22 so that fluid is free to pass upwardly through the open port 44 and into the outlet passage 31 within the annular space between the valve stem 29 and the inner wall of the hollow piston rod 22.. If desired, the reduced diameter portion 22' may be formed separately from the main portion 22 of the plunger rod and telescopically disposed and securely afiixed within its lower end by cement or the like.

By virtue of this arrangement the valve stem 29 not only functions as part of the frictional or yielding connection between the inlet valve 28 and the plunger rod 22, but in addition its withdrawal from the outlet passage 31 on each suction stroke of the plunger assembly 20 produces a suction or suck-back action in the passage 31 to prevent the dripping of fluid from the discharge head outlet.

The inlet valve 28 per se, its association and manner of cooperation with the valve port 16, are substantially as disclosed in my copending application Serial No. 318,- 683, filed October 24, 1963. Thus at its free inner end the valve 28 is formed with a radially inwardly projecting annular retaining rib 74 adapted to be snap fitted over the cooperating radially outwardly presented lugs or projections '76 at the free ends of the resiliently radially deflectable retainer fingers 78. It will be readily seen that the said fingers constitute integral portions of the tubular extension of the suction tube 18 inwardly from around the inlet valve port 16. These fingers 78 are circumferentially separated from each other to provide space for the entry of fiuid from the port 16 into the pump chamber 26 when the valve 28 is unseated on the suction stroke of the piston 24, as in FIGURES 1 and 3. The projections or lugs 76 of the retainer fingers are spaced axially a sufficient distance from the valve seat 3% to per mit free telescoping movement of the valve 28 over these fingers between its open position against the projections 76, as seen in FIGURE 3, and its seated or closed position as shown in FIGURE 4. In the closed position, the valve 28 has its free depending open end snugly received in and radially confined by engagement with the annular wall 49, with its axial end edge abutting in sealing relation against the seat 30.

In the operation of a dispensing pump as above described commencing with the parts positioned as in FIG- URES l and 3, axial finger pressure applied against the finger piece 35 of the discharge head will result in a downward or compression stroke of the plunger rod 22 in opposition to the upward pressure of the spring 23. This stroke will normally terminate somewhat short of the position illustrated in FIGURES 2 and 4, due to interference between the threads of the internally threaded collar 11 and the externally threaded collar 36 at the base of the discharge head 32. Prior to the commencement of this stroke, with the parts as in FIGURES 1 and 3, it will be apparent that though the inlet valve 28 is held open due to its frictional coupling to the plunger rod 22, the expansion of the spring 23 has urged the enlargement 42 of the plunger rod into sealing abutment against the annular rib 45' of the outlet valve 40, the upward move ment of the piston 24 having been arrested by abutment of its upper edge with the stop shoulder 58.

During the initial portion of the downward compression stroke, the frictional coupling between the plunger rod22 and the valve stem 29 will seat the inlet valve 28 to prevent backflow of fluid from the chamber 26 into the port 16. At the same time the piston 24 will have been retarded by its frictional engagement with the inner wall of the cylinder so that the resulting lost motion between the piston rod 22 and piston 24 will have caused relative movement of these parts such that the outlet valve 40 will have assumed an open position. In such position the valve port 44 is uncovered and the fluid compressed within the pump chamber 26 is free to escape upwardly through said port into the outlet passage 31 from which it is discharged through the discharge head 32 in known manner.

Thus at all times immediately following the initial portion of the compression stroke, the inlet and outlet valves will be in closed and opened positions respectively as shown in FIGURES 2 and 4.

As soon as pressure is removed from the finger piece 35 to permit the spring 23 to urge the plunger assembly upwardly on the suction stroke, the frictional coupling between the inlet valve and the plunger rod opens the inlet valve 28, while at the same time the ensuing lost motion between the plunger rod and the piston 24 functions to close the outlet port 44, with the result that the subsequent continuation of the suction stroke causes fluid to be drawn into the pump chamber 26 through the inlet port 16.

As earlier mentioned, the withdrawal of the valve stem 29 from the outlet passage 31 during the suction stroke produces a suck-back action in said passage to prevent the dripping of material from the orifice or outlet of the discharge head 32.

Sealing means In a dispensing pump of the type here involved, the ability to condition the pump against leakage during the shipping of filled containers is of importance. The present invention includes means for achieving this function substantially in the matter known in the art, by maintaining the plunger assembly depressed to actuate the various seals. In addition it includes provision of sealing means which are actuated under the action of the spring 23 in the fully projected position of the plunger assembly as in FIGURES l and 3.

To lock the plunger assembly in its fully depressed condition, as shown best in FIGURE 2, there is provided a known arrangement such as is illustrated in my prior Patent No. 3,084,873 in which the discharge head 32 has an externally threaded base 36 for engagement with the internally threaded collar 11. When the threaded portions of the base and collar are interengaged, to secure the plunger assembly in its fully depressed condition as in FIGURE 2, an axially projecting annular sealing rib 80 on the plunger discharger head 32 abuts in sealing relation against a shoulder within the collar 11. Also if desired there may be provided an annular sealing flange or fin 43 on the plunger discharge head for operative engagement with the outer or upper end of the collar 11.

The means above described resists leakage of fluid between the plunger assembly and cylinder outside of the normal discharge passages. The sealing reception of the piston skirt 25 in groove 54 prevents leakage of fluid from the pump chamber 26 past the piston. At the same time the axial abutment of the lower end section 22' of the plunger rod against the upwardly presented shoulder 82 of valve 28 maintains that valve in its fully seated position to prevent the passage of fluid through the port 16 into the pump chamber 26.

Where the containers are to be shipped with the plunger assemblies in their projected positions, the above mentioned means for locking the plunger assembly in depressed condition may be dispensed with. Thus in the fully projected positions as produced by the spring 23, the piston 24 covers the breathing opening 38 and also is urged into sealing engagement with the stop shoulder 58 at the upper end of the cylinder. The spring 23 at the 6 same time presses the enlargement 42 of the plunger rod 22 against the mating surface of the annular rib 45, while forcing the plunger rod in its entirety upwardly through the outlet valve 40 so that the port 44 is completely closed and sealed to prevent any passage of fluid from the pump chamber 26 into the outlet passage 31.

Assembly steps Attention is now directed to the fact that the several component parts of the pump structure above described are adapted for assembly in a particularly novel, simple and economical manner without the necessity for glue or cement. The arrangement is such that the plunger assembly and valves may be fully assembled primarily by snap or force fitting of certain parts past protuberances or enlargements in other parts. The several parts of the plunger and valve assemblies moreover may be guided into assembled relation merely by axial insertion into the cylinder through its open end. The several parts which are thus assembled are formed of a suitable plastic material having resilient flexibility and suflicient elasticity to permit this mode of assembly. It has been found that plastic materials such as polyethylene and polypropylene are well adapted for formation of the several parts.

In assembling the several parts within the pump cylinder 10, the formation of the annular retainer rib or boss 58 in the upper end of this cylinder is deferred until the final step. With the cylinder 10 held with its open end upwardly, the inlet valve 28 together with its unitary stem 29 is first dropped downwardly into the cylinder into a position in which it rests on the upper end of the retainer fingers 78. Following this the actuating spring 23 is dropped downwardly around the stem 29. It will be guided downwardly in centered relation about the valve 28 by a conical guide surface 82 which also serves as an abutment for engagement by the lower end of the re duced diameter plunger rod extension 22'. Both the lower end of the spring 23 and of the valve 28 therewithin will be axially centered with respect to the cylinder 10 by engagement of the lower end of the spring with the guide surface 52.

The piston 24 is then loosely inserted in the upper end of the cylinder around the upwardly projecting end of the valve stem 29, said upper end preferably being of conical shape to facilitate its reception in the reduced diameter extension 22' of the plunger rod 22. Then the plunger rod 22 is inserted into the cylinder 10 around the valve stem 29 and within the outlet valve or valve portion 40 of the piston. Its radial enlargement 42 will force the piston downwardly toward the position shown in FIG- URES 2 and 4 in abutting engagement with the closed end of the cylinder, following which continued inward thrusting of the plunger rod 22 forces the enlargement 42 through the sleeve valve 40 and downwardly past the radially projecting annular rib 45 which is stretched and deflected to permit its passage in the manner earlier described. At the same time the piston rod will move frictionally downwardly along the valve stem 29 until the free end of this reduced diameter extension 22' abuts against the shoulder 82 on the valve 28, whereupon continued movement of the plunger rod 22 then forces the retainer ring 74 of the valve downwardly beyond the radial projections 76 of the retainer fingers. The parts are formed with cooperating inclined or cam surfaces as is readily apparent to facilitate this action. The projections 76 will thereafter resist withdrawal of the valve 28 which will thus be free to move axially between the seated and unseated position.

With the parts thus retained in their positions as shown in FIGURES 2 and 4, the retaining annular shoulder or rib 58 is then formed in the upper end of the pump valve or cylinder 10 by a suitable swaging tool, all as more fully described in the earlier identified copendin'g application Serial No. 122,585. The discharge head 32 may subsequently be applied over the open upper end of the '7 hollow plunger rod 22 and secured in operative position by means of the snap rings and grooves 39 as illustrated or by any other suitable means.

In this application I have shown and described only the preferred embodiment of my invention. However, I recognize that the invention is capable of other and different embodiments and that its details may be varied in obvious manner without departing from the invention. Accordingly the foregoing description and drawings are to -be considered as merely illustrative in nature.

Having thus described my invention, I claim:

1. A reciprocating pump comprising a pump cylinder having an inlet port communicating with one end thereof, an annular piston disposed for axial reciprocation in said cylinder in fluid tight frictional sliding engagement with the inner wall of said cylinder, said piston and the closed end of said cylinder jointly defining a variable volume pump chamber, a tubular plunger rod extending coaxially through said piston for reciprocation in said cylinder and defining a pump outlet passage, said plunger rod being formed with an outlet port positioned to establish communication between said pump chamber and said outlet passage, said piston having an outlet valve affixed thereto for limited axial sliding movement on said plunger rod between open and closed positions with respect to said outlet port, cooperating means on said plunger rod and said piston for limiting said rod and piston to relative movement between said open and closed position, an inlet valve disposed in said pump chamber for axial movement to and from closing relation with respect to said inlet port, means yieldably interconnecting said inlet valve and said plunger rod for axial movement together, and means in said cylinder for limiting the axial movement of said inlet valve away from closing relation with respect to said inlet port.

2. A pump as defined in claim 1, in which said outlet port opens radially through said plunger rod, and said outlet valve is a sleeve valve arranged to cover and uncover said port as an incident to its axial movement with respect to said rod.

3. A pump comprising a pump cylinder having an inlet port communicating with one end thereof, an annular piston disposed for axial reciprocation in said cylinder in fluid tight frictional sliding engagement with the inner Wall of said cylinder, said piston cooperating with the closed end of said cylinder to define a variable volume pump chamber, a tubular plunger rod extending coaxially through said piston for axial reciprocation in said cylinder :and defining a pump outlet passage, said plunger rod having an end in said chamber formed with an axially directed opening of smaller cross-section than the discharge passage and communicating therewith and with a radially directed outlet port communicating with said outlet passage, said piston having an outlet valve aflixed thereto for limited axial sliding movement with said piston on :said plunger rod between open and closed positions with :respect to said outlet port, cooperating means on said :rod and said piston for limiting said rod and piston to :relative movement between said open and closed positions, an inlet valve disposed in said chamber for axial movement to and from closing relation with respect to :said inlet port, said inlet valve having a valve stem afiixed thereto and frictionally slidably disposed through said opening to yieldably interconnect said inlet valve and :said plunger rod for axial movement together, thereby said stem functions on each suction stroke of the pump plunger and piston to suck back fluids in the outlet passage, while the outlet valve remains closed to bar the return of any such fluids into the pump chamber.

4. A pump as defined in claim 1, further including spring means disposed in said pump chamber under compression between said plunger rod and the closed end of the chamber for resiliently urging said plunger rod through said outlet valve to relative positions wherein said valve doses s d p rt,

5. A pump as defined in claim 1, including a further valve means carried by said plunger rod within the pump chamber for axial movement into and from seated relation over one end of said sleeve valve, said outlet port being located on the axially remote side of said further valve means from the pump chamber.

6. In a pump structure the combination of elements including a pump cylinder having an inlet port communicating with one end thereof, an annular piston disposed for axial reciprocation in said cylinder in fluid tight frictional sliding engagement with the inner wall of said cylinder, said piston cooperating with the closed end of said cylinder to define a variable volume pump chamber, a tubular plunger rod extending coaxially through said piston for axial reciprocation in said cylinder and defining a pump outlet passage, said plunger rod being formed with a radially directed outlet port positioned to establish communication between said pump chamber and said outlet passage, said piston having a sleeve type outlet valve afiixed thereto for limited axial sliding movement relative to the plunger rod between open and closed positions with respect to said outlet port, and cooperating means on said rod and said piston for limiting the same to relative sliding movement between said open and closed positions.

7. The combination defined in claim 6 including spring means compressed between the plunger rod and one end of the cylinder for urging said plunger rod to an axial position with respect to the piston in which said outlet valve is closed.

8. The combination defined in claim 7 including a further valve means carried by said plunger rod within said pump chamber for axial movement into and from seated relation over one end of said sleeve valve, said outlet port being located on the axially remote side of said further valve means from the pump chamber.

9. A pump comprising a pump cylinder having an inlet port communicating with one end thereof, an annular piston disposed for axial reciprocation in said cylinder in fluid tight frictional sliding engagement with the inner wall thereof, said piston cooperating with the closed end of said cylinder to define a variable volume pump chamber, said annular piston defining an axial opening, a plunger rod snugly slidably disposed through said opening for axial reciprocation, said plunger rod defining a discharge passage having a port disposed for communication with said pump chamber, a valve means carried by said plunger rod for limited axial movement between seated and unseated positions with respect to said port, said valve means forming part of a lost motion connection for transmitting reciprocation from said rod to the piston whereby said lost motion moves the valve means between its seated and unseated positions incident to each reversal of the plunger stroke, an inlet valve disposed in said chamber for axial movement to and from closing relation with respect to said inlet port, means yieldably interconnecting said inlet valve and said plunger rod for axial movement together, and means in said cylinder for limiting the axial movement of said inlet valve away from closing relation with respect to said inlet port.

10. A pump as defined in claim 9, in which said passage is formed interiorly of the plunger rod, said port being radially directed and positioned axially on the rod for movement with the rod from an open position within said pump chamber to a closed position in which it is withdrawn from said pump chamber into said opening.

11. A pump as defined in claim 9, in which said plunger is provided internally with said discharge passage, said port opening from the plunger rod on the axially remote side of said valve means from the pump chamber.

12. A pump as defined in claim 1, in which said cooperating means on the rod and piston respectively for limiting their relative movement comprises an elastically extensible collar having an outer periphery integrally connected to said piston on the interior thereof and projecting radially into said opening for snug sliding engagement of its inner periphery with said plunger rod, and a radial enlargement on said plunger rod of greater diameter than the inner periphery of said collar for insertion through and expansion of said collar on initial assembly of said parts, said enlargement and said collar having abrupt axially presented and relatively opposed surfaces for positively resisting subsequent relative separation of said plunger rod and said piston.

13. A pump as defined in claim 12, in which said surfaces are annular and adapted for sealing engagement with each other, and spring means compressed between said enlargement and the closed end of the cylinder for resiliently urging said surfaces into sealing engagement.

References Cited by the Examiner UNITED STATES PATENTS 96,099 10/1869 Gates 103188 2,362,081 11/1944 Martin 103188 10 DONLEY I. STOCKING, Primary Examiner.

WARREN E. COLEMAN, Examiner. 

1. A RECIPROCATING PUMP COMPRISING A PUMP CYLINDER HAVING AN INLET PORT COMMUNICATING WITH ONE END THEREOF, AN ANNULAR PISTON DISPOSED FOR AXIAL RECIPROCATION IN SAID CYLINDER IN FLUID TIGHT FRICTIONAL SLIDING ENGAGEMENT WITH THE INNER WALL OF SAID CYLINDER, SAID PISTON AND THE CLOSED END OF SAID CYLINDER JOINTLY DEFINING A VARIABLE VOLUME PUMP CHAMBER, A TUBULAR PLUNGER ROD EXTENDING COAXIALLY THROUGH SAID PISTON RECIPROCATION IN SAID CYLINDER AND DEFINING A PUMP OUTLET PASSAGE, SAID PLUNGER ROD BEING FORMED WITH AN OUTLET PORT POSITIONED TO ESTABLISH COMMUNICATION BETWEEN SAID PUMP CHAMBER AND SAID OUTLET PASSAGE, SAID PISTON HAVING AN OUTLET VALVE AFFIXED THERETO FOR L IMITED AXIAL SLIDING MOVEMENT ON SAID PLUNGER ROD BETWEEN OPEN AND CLOSED POSITIONS WITH RESPECT TO SAID OUTLET PORT, COOPERATING MEANS POSITIONS WITH RESPECT TO SAID SAID PISTON FOR LIMITING SAID ROD AND PISTON TO RELATIVE MOVEMENT BETWEEN SAID OPEN AND CLOSED POSITION, AND INLET VALVE DISPOSED IN SAID PUMP CHAMBER FOR AXIAL MOVEMENT TO AND FROM CLOSING RELATION WITH RESPECT TO SAID INLET PORT, MEANS YIELDABLY INTERCONNECTING SAID INLET VALVE AND SAID PLUNGER ROD FOR AXIAL MOVEMENT TOGETHER, AND MEANS IN SAID CYLINDER FOR LIMITING THE AXIAL MOVEMENT OF SAID INLET VALVE AWAY FROM CLOSING RELATION WITH RESPECT TO SAID INLET PORT. 